Just over a week ago, U.S. President Barack Obama announced the release of the last U.S. prisoner of war in Afghanistan, 28-year-old Sgt. Bowe Bergdahl, who was held by the Haqqani network, a Taliban affiliate, for five years.

Instead of sparking a national celebration, Bergdahl's recovery touched off a debate about the circumstances in which he vanished. He allegedly walked off his base in Afghanistan, on June 30, 2009, leaving behind his armor and weapons, carrying just a backpack, water, knives and a notebook, The New York Times reported. Soon after, Bergdahl was captured. Some of his fellow soldiers have called him a deserter, and others have gone so far as to blame him for the deaths of six service members who were involved in the search for him, according to news reports.

Experts who spoke to Live Science adamantly said that the facts of Bergdahl's disappearance from his base remain murky. The soldier is recovering at a U.S. military hospital in Germany, and he hasn't spoken to his parents yet, according to media reports. While more information is bound to surface in the weeks ahead, in the meantime, Live Science looks at some of the questions the Bergdahl case has raised: What is desertion? How common is it? What will happen to Bergdahl?

What is desertion?

Desertion is leaving your place of duty with the intention of remaining away permanently. It's sometimes confused with going AWOL, or absent without leave, but the main difference is that deserters have the intent to never return. [The 10 Most Outrageous Military Experiments]

"It's a common myth that you have to be gone for at least 30 days [to be considered a deserter]," said James Branum, legal director of the Oklahoma Center for Conscience in Action. "But you could desert and be gone one hour as long as you meet that intent requirement."

That said, the bar for proving someone had intent never to return is quite high. In Bergdahl's case, determining his intentions will likely be based upon interviews with Bergdahl as well as his fellow soldiers, and possibly other evidence, like a note, Branum said.

How many soldiers desert?

From 1981 to 2007, less than 1 percent of soldiers deserted during each fiscal year, according to figures provided by the military. The U.S. Army counted 2,659 deserters (or 0.53 percent of troops) in 2005, followed by 3,301 (0.67 percent) in 2006 and 4,698 (0.93 percent) in 2007 — the most recent year for which the military provided such numbers.

Desertion has never been higher since 1971, when more than 33,000 soldiers deserted.Credit: by Ross Toro, Infographics Artist

Though the statistics show a slight rising trend over those last few years, the Army contends that desertion isn't a widespread problem and that most cases don't have to do with political objections to war.

"The vast majority of American soldiers serve their country admirably and honorably," an Army spokesperson said. "Studies have shown that most soldiers desert because of personal, family or financial problems, not for political or conscientious-objector purposes."

The rates of desertion — and the reasons for it — have changed over the last 100 years in the U.S. military. There were 50,000 American deserters during World War II, said Charles Glass, former ABC News foreign correspondent and author of "The Deserters: A Hidden History of World War II" (Penguin Press HC, 2013).

"In World War II, the soldiers for the most part deserted because they were having nervous breakdowns," Glass said. That changed during the Vietnam War, when desertions as a matter of conscience were more common. In 1971, at the height of the Vietnam War, 33,094 American soldiers (3.41 percent of the Army) deserted, according to military figures.

In comparison, the numbers today are much smaller, likely because soldiers enlist voluntarily, said John Altenburg, a former lawyer for the U.S. Army and a retired major general, who now works for the private firm Greenberg Traurig.

Who goes missing?

Army officials say deserters are likely to be first-term, junior-enlisted soldiers; about 60 percent of deserters have served less than 1 year and more than 80 percent have served less than 3 years.

Bergdahl, who was 23 when he disappeared, seems to fit that profile. He enlisted in the Army in the spring of 2008, arrived in Afghanistan in March 2009 and slipped away from his outpost the night of June 30, 2009. But he had also expressed discontentment with the Army and disillusionment with the war effort in emails to his family published by Rolling Stone in 2012.

"The US army is the biggest joke the world has to laugh at," Bergdahl wrote in one email, days before he went missing. "It is the army of liars, backstabbers, fools, and bullies. The few good SGTs are getting out as soon as they can, and they are telling us privates to do the same."

Will Bergdahl face punishment?

Army personnel will be preoccupied with Bergdahl's physical and mental health, as well as learning about his capture and imprisonment, before they deal with the accountability issue and decide whether or not he needs to be prosecuted or charged with desertion, Altenburg said.

But there are several different courses of action the individuals in Bergdahl's chain of command could take, depending on what they learn in their investigation, Altenburg explained. They could decide to take no action and keep Bergdahl in the Army. They could pursue a nonjudicial punishment, which could result in 45 days of extra duty and a reduction in rank. They could seek to obtain an administrative discharge, which includes an honorable discharge, a general discharge under honorable conditions and an other-than-honorable discharge.

Or, the case could be dealt with in a court martial, which could result in a bad conduct discharge or — the most serious consequence — a dishonorable discharge, which is the military equivalent of a felony conviction. The maximum punishment for desertion in a time of war is death, though the Army says no one has been dealt this penalty during the wars in Afghanistan and Iraq. The maximum sentence for a solider convicted of desertion with intent to avoid hazardous duty or shirk important service is 5 years of confinement. Even if Bergdahl is tried and found guilty, it's unlikely that he would face such a sentence, because of the harsh conditions he's already endured at the hands of the Taliban while in captivity, both Altenburg and Branum said.

Branum said the Bergdahl case highlights the lack of information soldiers have about their legal options under the law (like the right to file for conscientious objector status) if they're having a crisis of conscious during deployment.

"My hope is people don't find themselves in situations like this," Branum said. "At some point, they're going to have to face the music."

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Megan Gannon

Megan started writing for Live Science and Space.com in 2012. Her interests range from archaeology to space exploration, and she has a bachelor's degree in English and art history from New York University. Megan spent two years as a reporter on the national desk at NewsCore. She has watched dinosaur auctions, witnessed rocket launches, licked ancient pottery sherds in Cyprus and flown in zero gravity. Follow her on Twitter and Google+.